Methodological challenges to confirmatory latent variable models of social vulnerability

Natural Hazards - Socially vulnerable communities experience disproportionately negative outcomes following natural disasters and underscoring a need for well-validated measures to identify those...     

Development and validation of a novel-based combination operational air quality forecasting system in Greece

In the present work, a model combination is developed in order to provide the public, in north-western Greece, with the next day air quality forecast. Generally, the development and deployment of a real-time numerical air quality prediction system is technically challenging while even more in complex terrain. The Air Pollution Model (TAPM) (http://www.cmar.csiro.au/research/tapm) is a hydrostatic prognostic mesoscale model. It has been calibrated for the area in recent studies and used in air quality assessments. In 2007, TAPM has started operating in a real-time operational mode for the prediction of next day’s weather forecast, particulate matter (PM₁₀ with an aerodynamic diameter <10 μm) daily average concentration and Air Pollution Indexes. The model setup is a link up between TAPM and SKIRON modeling system (http://forecast.uoa.gr).     

The silica supersaturated waters of northern Evia and eastern central Greece

The area of north Evia and eastern central Greece is characterized by strong geomorphological contrast and is built up mainly of consolidated rocks. Unconsolidated young sediments of Pleistocene to Holocene age cover the valley and basin flats, forming the most productive aquifers in this area. However, two more types of aquifers can be distinguished within the consolidated rock area. The first one is associated with karstified limestones and the second with strongly tectonized ultramafic rocks. The schist–chert formation, with intercalations of shales and cherts, seals the ultramafic masses underneath. Surface and spring waters associated with ultramafic rocks in north Evia and eastern central Greece were studied. Two types of water can be distinguished: (1) high Mg²⁺ and SiO₂ , bicarbonate as the dominant anion, pH 7·4–9·2, temperature 9·5–16·3 °C, low TDS (total dissolved solutes) (459–1037 mg/l), found both in peridotite and serpentinite areas, classified as Mg–HCO₃ type; (2) high Ca²⁺, low Mg²⁺ and SiO₂ , hydroxyl ion as the major anion, pH 11·2, temperature 28 °C, very low TDS (122 mg/l), found in peridotite areas, classified as Ca–OH type. The studied waters are highly supersaturated with respect to quartz, amorphous silica, brucite and most low temperature magnesium silicates (antigorite, sepiolite, talc, etc.). These waters show relatively narrow SiO₂ concentration ranges and a trend parallel to the amorphous silica saturation surface. The silica supersaturated waters have the potential to precipitate silica and consequently could affect the people of the local communities that use it as drinking water, causing health problems (kidney stones). Copyright © 1999 John Wiley & Sons, Ltd.     

Contribution to the study of thermal waters in Greece: chemical patterns and origin of thermal water in the thermal springs of Lesvos

The occurrence of thermal/spa waters on Lesvos Island is related to the presence of a major faulting system. Thermal waters are the result of mixing of meteoric and infiltrating seawater at great depth, and their total salinity depends on the percentage of seawater in their composition. According to the diagrams of main elements, trace elements and environmental isotopes, most of the components that determine the chemical composition of thermal waters such as sodium, chloride and sulphates originate from seawaters. On the other hand, the concentration of calcium, magnesium, boron, lithium, etc., was affected by water–rock interaction under high temperature conditions. Moving towards the surface, thermal waters may become polluted by influx of recent seawater, allowing their chemical composition to become similar to that of seawater. The thermal waters of Lesvos Island present relatively high concentrations of ammonia and redox sensitive metals because they are hosted in a reducing environment. They also exhibit low nitrate concentrations due to their mixture with recent fresh water. Finally, they show increased radon concentrations, ranging from 20 to 60 kBq m^?3 in the eastern and southern parts of the island, and about 230 kBq m^?3 in the north, in the area of Eftalou–Argenos. Copyright © 2007 John Wiley & Sons, Ltd.     

Diagnosis of groundwater quality and assessment of contamination sources in the Megara basin (Attica,Greece)

In this study, hydrochemical analysis, statistical analysis and GIS database have been successfully used to explain the main factors and mechanisms controlling the distribution of major and trace elements in groundwater. The groundwater of Megara basin is subject to intense exploitation to accommodate all the water demands of this agricultural area. Water quality data obtained from 58 sampling sites of the Megara basin, aims to describe groundwater quality in relation to geology and anthropogenic activities. Factor analysis revealed that four factors accounted for 79.96% of the total data variability. The contribution of each factor at sampling sites was calculated. Evaluation of water samples by comparing quality standards and levels recorded in the literature for both drinking and irrigation uses is discussed.     

The chemical composition of the surface system of Peneos river, Thessaly/Central Greece

 Peneos is the mainstream for the drainage of Thessaly's basin. It contributes significantly in recharging the aquifers, as well as to the direct irrigation water, since there is intense agricultural activity in the basin of Thessaly. The investigation of the hydrochemical conditions of the surface water system of Peneos showed that the chemical composition is related to the lithology of the aquifers of the basin, the anthropogenic influence and the biological activity. The chemical composition of this system changes in time and space. The salinity decreases during the winter period, in contrast to the summer period when it increases drastically. The lower values of TDS appear in the upstream part of the river (95–124 mg/l) whereas downstream, the values of TDS increase significantly (400–632 mg/l). The hydrochemical type Ca-Mg-HCO₃ dominates the largest part of the river while it changes to NA-Cl in the estuary. The concentrations of the dissolved species in the main Peneos river are higher than in the spring waters. Peneos is the most polluted river in Greece. The concentration of the pollutants is higher at the downstream part of the river, but is lower than the accepted upper limits. The use of the surface water of the system of Peneos river for irrigation purposes based on the SAR factor is acceptable because the absorption ratio for Na and salinity are low and medium respectively. Received: 27 October 1997 · Accepted: 21 September 1998     

Groundwater quality in Mesogea basin in eastern Attica (Greece)

Studies on the hydrogeological conditions of the Mesogea basin in east Attica reveal that the aquifers developed on the post‐alpine formations at the inner part of the coastal brackish zone exhibit positive hydraulic head. These Neogene and Quaternary deposits present high salt concentrations. Selected points were sampled (total 85: 51 wells and 34 boreholes) in order to obtain hydrogeological and hydrochemical data for a better understanding of the structure, operation and dynamics of the aquifer of the area. Statistical methods, R‐mode factor analysis and scatter‐plot diagrams were used for the hydrochemical analysis and presentation of the data. The groundwater resources are relatively weak and there is significant quality degradation due to the geological structure of the greater area, as well as the bad management of the aquifer and anthropogenic activities. Groundwater is characterized by high salt concentrations. Electrical conductivity values range between 260 and 6970 µS cm^?1. High salt concentrations at the coastal aquifers are due to sea intrusion, whereas they are attributed to the dissolution of minerals of the geological environment in the inland area. The groundwaters of the study area can be classified into five water types: Ca–HCO₃, Mg–HCO₃, Na–HCO₃, Na–Cl and Mg–Cl. They are saturated in dolomite and calcite, whereas they are unsaturated in anhydrite. High ion concentrations, e.g. ] (0‐221 mg l^?1), ] (0·01‐1·88 mg l^?1), ] (0·01‐6·75 mg l^?1), as well as high heavy metals concentrations are attributed to anthropogenic impacts. Copyright © 2006 John Wiley & Sons, Ltd.     

Thresholds of TEC variability describing the plasmaspheric disturbed state

A classification of the TEC variability is attempted in order to describe the disturbed states of the ionosphere and plasmasphere. Four different disturbed states are distinguished, according to the amplitude of TEC variability. Remarks are made regarding the variability and geomagnetic storms.